Reclaimed water recycling process for high-speed service area

Abstract

The invention relates to the technical field of reclaimed water recycling, and particularly discloses a high-speed service area reclaimed water recycling process which comprises the following steps: step 1, fibrous membrane filtration: filtering wastewater by adopting a fibrous membrane; 2, activated carbon filtration: enabling the effluent in the step 1 to pass through an activated carbon adsorption device; step 3, sodium hypochlorite sterilization: sodium hypochlorite is added into the effluent obtained in the step 2; step 4, intercepting iron and manganese ions: intercepting metal ions from the effluent in the step 3 by using a mixed filter material; step 5, precise filtration: intercepting particulate matters from the effluent in the step 4 by adopting a PP cotton filter element; and step 6, reverse osmosis process: desalting and purifying the filtered water in the step 5 through a reverse osmosis membrane assembly, and collecting reverse osmosis produced water as recycled water reaching the standard. The technical problem that the brake spray water cannot be supplemented to a truck in the service area in time due to the fact that reclaimed water recycled by a reclaimed water recycling technology in the high-speed service area cannot meet the requirement of the brake spray water is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of reclaimed water reuse, and in particular to a process for reclaiming reclaimed water in a highway service area. Background Art

[0002] While providing convenient services to drivers and passengers, highway service areas also face increasing water demands. Water supply in service areas is generally divided into two categories: 1. Service areas near urban or rural water plants can rely on their water supply; 2. Service areas located far from cities, towns, or villages face difficulties in sourcing water, and typically rely on self-built water supply systems, using groundwater or surface water. However, these self-built water supply systems are affected by the availability of water sources at the service area's location. The groundwater or surface water sources themselves are affected by climate, resulting in seasonal fluctuations in water levels and water supply, leading to indirect water shortages in these service areas.

[0003] In order to ensure water supply in water-scarce service areas, these service areas usually use reclaimed water reuse technology to treat the domestic wastewater in the service stations for reuse. For example, the patent document with application number CN201610371445.X discloses a highway service area sewage treatment device and method, which is equipped with multiple biochemical reaction pools and filtration tanks, and uses a combination of "biochemical and physical-chemical" methods to treat the wastewater, and finally obtain reclaimed water that can be reused.

[0004] This technology treats wastewater in service areas for reuse, alleviating water shortages in highway service areas. However, trucks traveling on highways require refills of brake water at service areas. Brake water typically refers to the water in the brake spray systems used on heavy trucks. These systems spray water onto the brake drums, utilizing the heat absorbed by evaporation to reduce drum temperature and ensure safe braking. If the spray water is depleted and not promptly replenished at the service area, the brake drums can overheat during braking, leading to brake failure. In severe cases, tires can spontaneously combust due to inadequate heat dissipation, posing a risk. Therefore, service areas typically provide refills of brake water for trucks to ensure sufficient water supply during highway travel. Service areas with their own water supply systems cannot guarantee a sufficient supply of fresh water during water shortages. The only option is to reuse the wastewater, which comes from various sources in the service station. When used for the first time, the water may come into contact with a large amount of ferrous metals (such as cleaning metal tools, rusted water pipes in the service station, truck cooling pools, etc.), causing the wastewater to contain iron and manganese ions. The recycled water reused in the prior art is only a routine treatment of the wastewater, which can only reach the level of miscellaneous water and can be used for watering, washing the floor, and cleaning. However, as brake spray water, the water contains a large amount of metal ions, which will corrode the metal parts of the brake system, causing damage to the entire brake system. Therefore, in water-scarce service areas, some trucks encounter only recycled water. When they are unable to replenish qualified brake spray water in time in the service area, and do not want to damage the brake parts due to the use of recycled water, they can only take the risk of driving to the next service area to replenish water. Often in this process, due to the lack of brake spray water, the truck cannot dissipate heat in time when braking, resulting in accidents. Therefore, the market urgently needs a method that can treat the recycled recycled water to meet the brake water requirements. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-speed service area reclaimed water reuse process to solve the technical problem mentioned above that the existing technology of high-speed service area reclaimed water reuse technology cannot treat the metal salts in the wastewater, so the reused reclaimed water cannot meet the brake spray water requirements, making it impossible for trucks in the service area to replenish brake spray water in time.

[0006] In order to solve the above problems, the technical solution adopted by the present invention is as follows: a high-speed service area water reuse process, characterized in that it includes the following steps:

[0007] Step 1, fiber membrane filtration: use fiber membrane to perform primary filtration treatment on wastewater;

[0008] Step 2, activated carbon filtration: the effluent from step 1 is passed through an activated carbon adsorption device to remove inorganic particles and organic matter;

[0009] Step 3, sodium hypochlorite sterilization: adding sodium hypochlorite solution to the effluent of step 2 to perform contact sterilization;

[0010] Step 4, iron and manganese ion interception: using mixed filter media to intercept the metal ions in the water body after disinfection in step 3;

[0011] Step 5, precision filtration: Use precision PP cotton filter element to intercept micron-level particles in the water discharged from step 4;

[0012] Step 6, reverse osmosis process: the filtered water in step 5 is passed through a reverse osmosis membrane assembly for desalination and purification, and the reverse osmosis produced water is collected as qualified recycled water.

[0013] The beneficial effects of this embodiment are:

[0014] There are two main reasons why recycled greywater cannot be used as brake spray water. First, it contains large amounts of manganese and iron ions. These ions form galvanic cells on the surfaces of metal components in the brake system, corroding them and causing them to rust, rapidly reducing their service life. Second, recycled greywater can easily form scale in the spray system, clogging the spray nozzles. Scale formation is not solely due to excessive supersaturation of inorganic salts in the water. Organic matter and microorganisms can also serve as scale nuclei. Substances such as organic matter and proteins adsorb onto the surfaces of pipes and equipment, forming organic films, while microorganisms such as bacteria and algae form biofilms. These organic and biofilms promote scale deposition. Therefore, if recycled greywater is to be used as brake spray water, it must be filtered to remove metal ions such as iron and manganese, and sterilized. Existing water treatment technologies typically use manganese sand filtration to remove iron and manganese ions, while sodium hypochlorite disinfection is commonly used to remove bacteria and microorganisms. The two are simply combined. First, the reclaimed water is filtered with manganese sand, and then sterilized with sodium hypochlorite after filtration. Based on this idea, the treated reclaimed water is basically free of manganese, iron ions and bacteria. The recycled reclaimed water can be used as brake spray water, but when it is converted, it is found that sodium hypochlorite will produce chloride ions when it decomposes in water, and chloride ions are a "catalyst" for metal corrosion: for iron (Fe): chloride ions destroy the oxide film on the surface of iron and promote the oxidation of iron (generating Fe2 + / Fe3 +), forming rust. For stainless steel: chloride ions may cause pitting corrosion or stress corrosion cracking (especially at high temperatures or high concentrations). For copper and aluminum: chloride ions react with metals to form soluble chlorides (such as CuCl2, AlCl3), which intensify corrosion. Therefore, simply combining the two, although the metal ions such as iron and manganese ions and microorganisms such as bacteria in the recycled water are removed, the introduced chloride ions will still corrode the metal components of the brake system. Therefore, simply combining the two cannot make the recycled water usable as brake spray water, and the chloride ions in the recycled water need to be removed. How to remove chloride ions becomes the key to the application of recycled water in brake spray water. Therefore, the process of this application adds a reverse osmosis process at the end, which uses the reverse osmosis process to remove chloride ions, so that the iron, manganese ions and bacterial microorganisms in the recycled water meet the standards while avoiding the introduction of chloride ions.

[0015] 2. After the introduction of reverse osmosis process, it can be guaranteed that the recycled water does not contain chloride ions, but sodium hypochlorite is added to the recycled water for sterilization and disinfection. The recycled water of highway service stations is wastewater used in daily life, and its water quality fluctuates. However, the sodium hypochlorite added in the process is constant over a period of time, which makes it often impossible for the sodium hypochlorite to be completely consumed. It follows the water into the reverse osmosis process, resulting in a large amount of residual chlorine in the reverse osmosis process. Residual chlorine refers to the free chlorine produced by the unconsumed sodium hypochlorite in the recycled water, such as hypochlorous acid (HOCl) and hypochlorite ions (ClO - ), these substances have very strong oxidizing properties. And the membrane used in the reverse osmosis process is made of polyamide or other polymer materials, and is very sensitive to oxidants. Oxidants can cause the degradation of membrane materials, thereby affecting the separation performance and the service life of the membrane. To this end, the application adjusts the process of sodium hypochlorite sterilization and disinfection to between the activated carbon filtration process and the manganese sand filtration process. Sodium hypochlorite sterilizes and disinfects the bacteria in the wastewater. When residual chlorine is present in water quality fluctuations, residual chlorine will follow the wastewater into the manganese sand filter. Residual chlorine will pre-oxidize the manganese and iron ions in the wastewater. Pre-oxidation can consume residual chlorine to the extreme, so that the reverse osmosis process does not contain residual chlorine. And after pre-oxidation of the water body, the removal effect of the manganese sand filter on manganese and iron ions can be enhanced. After multiple tests, it has been proven that residual chlorine pre-oxidation can significantly enhance the manganese removal effect. The manganese removal rate of the effluent is as high as over 90%. Therefore, the present application sets the sodium hypochlorite sterilization and disinfection process between the activated carbon filtration process and the manganese sand filtration process. It can not only cope with the problems of wastewater quality fluctuations, inability to completely consume sodium hypochlorite, and residual chlorine causing damage to the reverse osmosis membrane, but also enhance the filtration effect of the manganese sand filtration process on iron and manganese ions, killing two birds with one stone.

[0016] Furthermore, the mixed filter material in step 4 is manganese sand and modified quartz sand with a manganese active filter membrane on the surface as the mixed filter material.

[0017] Furthermore, in step 4, the manganese sand and modified quartz sand are arranged in layers, and the ratio of the layer thickness is manganese sand: modified quartz sand is equal to 2-4:6-8.

[0018] Furthermore, in step 4, the particle size of the manganese sand is 1.0-1.5 mm, and the particle size of the modified quartz sand is 0.3-0.6 mm.

[0019] Furthermore, the preparation method of the modified quartz sand includes: S1, preparing a saturated NaSiO3 solution; S2, adding natural quartz sand and active manganese oxide in the backwash wastewater of the water plant into the solution and stirring uniformly to obtain a mixture; S3, heating and evaporating the mixture in S2 to obtain modified quartz sand.

[0020] Furthermore, the volume ratio of the saturated NaSiO3 solution, natural quartz sand and active manganese oxide is 1:2:2. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a process flow chart of the present invention,

[0022] Figure 2 It is a schematic diagram of the production equipment structure of the present invention. DETAILED DESCRIPTION

[0023] The following is further described in detail through specific implementation methods:

[0024] The reference numerals in the accompanying drawings of the specification include: .

[0025] Implementation example Figure 1-2 As shown:

[0026] Example 1

[0027] A high-speed service area reclaimed water recycling process comprises the following steps:.

[0028] Step 1, fiber membrane filtration: use fiber membrane to perform primary filtration treatment on wastewater;

[0029] Before the wastewater enters the fiber membrane filtration, a screen machine must be installed with a grid pitch of ≤5mm. The screen is mainly used to remove large particles of impurities and prevent them from clogging the fiber membrane. The fiber membrane assembly uses a hollow fiber ultrafiltration membrane with a pore size of 0.01-0.1μm. During operation, the water inlet pressure is set to 0.1-0.3MPa, and the transmembrane pressure difference is ≤0.15MPa. Backflushing is performed regularly using a mixture of 0.3MPa compressed air and clean water. Backflushing is performed regularly. In this embodiment, backflushing is performed every 2 hours.

[0030] Step 2, activated carbon filtration: the effluent from step 1 is passed through an activated carbon adsorption device to remove inorganic particles and organic matter;

[0031] The activated carbon filtration process uses coconut shell activated carbon filled in an activated carbon tank. The iodine value of the coconut shell activated carbon is ≥1000mg / g, and the particle size is 2-4mm. The water inlet of the activated carbon filtration process is located at the bottom of the tank, and the outlet is located at the top of the tank, allowing water to flow from bottom to top. Gravity traps particulate matter at the bottom of the activated carbon tank. New carbon is added at an annual loss rate of 15%, ensuring a carbon layer thickness of ≥2m. When adding new carbon, the activated carbon at the bottom of the tank is replaced first.

[0032] Step 3, sodium hypochlorite sterilization: adding sodium hypochlorite solution to the effluent of step 2 to perform contact sterilization;

[0033] Sodium hypochlorite is added directly to the water flowing out of the activated carbon filtration process for sterilization and disinfection. Sodium hypochlorite can be added directly to a solution prepared using sodium hypochlorite salt. The concentration of the sodium hypochlorite solution is controlled at 10%, and the effective chlorine dosage is 5-8 mg / L. A sodium hypochlorite generator can also be used to directly generate the sodium hypochlorite solution. After sterilization with sodium hypochlorite, the water passing through the activated carbon filtration process must be mixed with air using a pipeline mixer. A Venturi gas mixer can be used as the pipeline mixer. After mixing, the water enters the iron and manganese ion retention process.

[0034] Step 4, iron and manganese ion interception: using mixed filter media to intercept the metal ions in the water body after disinfection in step 3;

[0035] The mixed filter media used in the iron and manganese ion retention process is natural manganese sand and modified quartz sand. The preparation process of the modified quartz sand is as follows:

[0036] S1, prepare saturated NaSiO3 solution;

[0037] S2. Add natural quartz sand and active manganese oxide from backwash wastewater of a water plant to the solution prepared in S1 and stir to obtain a mixture. The mixture has a mass solid-to-liquid ratio of 75% and a mass ratio of natural quartz sand to active manganese oxide of 1:1.

[0038] The quartz sand needs to be repeatedly rinsed with deionized water to remove surface dust and impurities, and then dried. The active manganese oxides in the backwash wastewater of the water plant refer to the suspended solid matter in the backwash water in the sewage treatment plant using the pure manganese sand filtration process, which is precipitated, centrifuged, and dried to form a mud cake.

[0039] S3. Heat and evaporate the mixture in S2 to obtain modified quartz sand.

[0040] The particle size of natural manganese sand is 1.0-1.5mm, and the particle size of modified quartz sand is 0.3-0.6mm. The ratio of the two is manganese sand: modified quartz sand is 2:8;

[0041] In the filtration process, a tank is also used for filtration. The tank can be filled in layers, with the lower layer filled with modified quartz sand and the upper layer filled with natural manganese sand.

[0042] Step 5, precision filtration: Use precision PP cotton filter element to intercept micron-level particles in the water discharged from step 4;

[0043] The precision filtration filter element is installed with a cascade PP cotton filter element with a pore size gradient design from 5μm to 1μm. The filter element should be replaced every 15 days.

[0044] Step 6, reverse osmosis process: the filtered water in step 5 is passed through a reverse osmosis membrane assembly for desalination and purification, and the reverse osmosis produced water is collected as qualified recycled water;

[0045] The reverse osmosis membrane system uses a spiral RO membrane, with membrane materials including but not limited to Dow BW30-400, arranged in a single row of four horizontal tubes. Water passing through the reverse osmosis process is directly stored in a clean water storage tank.

[0046] Example 2

[0047] The difference between Example 2 and Example 1 is that in the example, manganese sand and modified quartz sand are mixed evenly before filling, and the ratio of manganese sand to modified quartz sand is 4:6.

[0048] And the preparation method of the modified quartz sand is as follows:

[0049] S1. Prepare 0.5 mol / L potassium permanganate solution and adjust the solution pH to 3-5;

[0050] S2. Mix the pretreated quartz sand with potassium permanganate solution in a mass ratio of 1:3-1:5. Stir and react in a constant temperature water bath (30-60°C) for 2-6 hours, and allow to stand for aging for 12-24 hours to obtain a mixture.

[0051] The quartz sand is repeatedly rinsed with deionized water to remove surface dust and impurities, and then dried for later use.

[0052] S3, separating the solid and liquid of the mixture in S2 to obtain a solid product, and drying the solid product at 60-100° C.; after drying, calcining at 200-400° C. for 2-4 hours to obtain modified quartz sand with a stable manganese active filter membrane.

[0053] The above is only an embodiment of the present invention, and the common knowledge such as the specific structure and characteristics of the scheme is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several variations and improvements can be made, which should also be regarded as the scope of protection of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A high-speed service area water reuse process, characterized by: The following steps are involved: Step 1, fiber membrane filtration: use fiber membrane to perform primary filtration treatment on wastewater; Step 2, activated carbon filtration: the effluent from step 1 is passed through an activated carbon adsorption device to remove inorganic particles and organic matter; Step 3, sodium hypochlorite sterilization: adding sodium hypochlorite to the effluent of step 2 to perform contact sterilization; Step 4, iron and manganese ion interception: the water body disinfected in step 3 is subjected to metal ion interception treatment using a mixed filter material, wherein the mixed filter material is manganese sand and modified quartz sand with a manganese active filter membrane on the surface as the mixed filter material; Step 5, precision filtration: Use precision PP cotton filter element to intercept micron-level particles in the water discharged from step 4; Step 6, reverse osmosis process: the filtered water in step 5 is passed through a reverse osmosis membrane assembly for desalination and purification, and the reverse osmosis produced water is collected as qualified recycled water.

2. The high-speed service area reclaimed water reuse process according to claim 1, characterized in that: In step 3, after the sodium hypochlorite sterilization, air needs to be mixed into the water body, and after being mixed with air, the water flows to the iron and manganese ion interception process in step 4.

3. The high-speed service area reclaimed water reuse process according to claim 1, characterized in that: The ratio of manganese sand to modified quartz sand in the mixed filter material in step 4 is 2-4:6-8.

4. The high-speed service area reclaimed water reuse process according to claim 3, characterized in that: In step 4, the manganese sand and modified quartz sand are arranged in layers, and the ratio of the layer thickness is manganese sand: modified quartz sand equal to 2:

8.

5. The high-speed service area reclaimed water reuse process according to claim 3, characterized in that: In step 4, the particle size of the manganese sand is 1.0-1.5 mm, and the particle size of the modified quartz sand is 0.3-0.6 mm.

6. The high-speed service area reclaimed water reuse process according to claim 3, characterized in that: The preparation method of the modified quartz sand includes: S1, prepare saturated NaSiO3 solution; S2, adding natural quartz sand and active manganese oxide from backwash wastewater of a water plant and stirring uniformly to obtain a mixture; S3. Heat and evaporate the mixture in S2 to obtain modified quartz sand.

7. The high-speed service area reclaimed water reuse process according to claim 6, characterized in that: The solid-liquid ratio of the mixture in S2 is 75%, and the mass ratio of natural quartz sand to active manganese oxide is 1:

1.

8. The high-speed service area reclaimed water reuse process according to claim 1, characterized in that: The sodium hypochlorite added in step 4 is a 10% sodium hypochlorite solution.

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